Certain clinical and morphologic findings are described in 67 patients (aged 23 to 76 years [mean 52], 55 women [82%] who had mitral valve replacement for mitral stenosis (with or without associated regurgitation) and simultaneous tricuspid valve replacement for pure tricuspid regurgitation (58 patients) or tricuspid stenosis (all with associated regurgitation) (9 patients). Of the 58 patients with pure tricuspid regurgitation, 21 had anatomically normal tricuspid valves and 37 had anatomically abnormal (diffusely fibrotic leaflets) tricuspid valves. Among these 58 patients, no clinical or hemodynamic variable was useful preoperatively in distinguishing the group without from the group with anatomically abnormal tricuspid valves. All 9 patients with stenotic tricuspid valves had anatomically abnormal tricuspid valves. The latter group had lower average right ventricular systolic pressures (tricuspid valve closing pressures) than the groups with pure tricuspid regurgitation, and none had severe pulmonary arterial hypertension (present in 20 [30%] of the 58 patients with pure tricuspid regurgitation).